[Adult Chiari malformation--five operative cases].

Recently, the diagnosis of adult Chiari malformation seems to have easy, because of the development of high resolution CT. During the last two years, we experienced with five cases of adult Chiari malformation diagnosed by CT metrizamide myelography. There were two males and three females aged from 15 to 55 years. Three cases had both foramen magnum compression and cerebellar symptoms. One of them had lower cranial nerve symptoms too. Another case had central cord symptoms, and the rest of them complained only of headache and vertigo. All cases underwent suboccipital craniectomy and upper cervical laminectomy. After operation, the cerebellar symptoms improved remarkably. Some of the central cord symptoms improved too. In one case with headache and vertigo, the result was unsuccessful. All cases were followed up in the outpatient clinic more than one year after operation. One case unchanged. Another case deteriorated seven months after surgery. The other three cases were in good condition. Operated cases of adult Chiari malformation are relatively rare in Japan. However, this type of malformation can be found easily by CT metrizamide myelography. A good many patients should be operated on carefully in consideration of their symptoms and severities.